Telephone system



April 2, 1946.. R, Q AVERY 2,397,529

TELEPHONE SYSTEM l Filed Sept. 26, 1944 9 Sheets-Sheet 2 OFFICE GROUP /NVE R. C AVERY April 2, 1946. I R. C. AVERY 2,397,829

' TELEPHONE SYSTEM Filed sept. ze, 1944 v9 sheets-sheet s /NVENTOR R. C. AVE RV 'BKM/M- April 2, 41946. R. c. AVERY 2,397,829

I TELEPHONE SY`STEM n v Fi1edfsept.-2, 1944 9 sheets-sheet 4 /Nl/ENTO? R. C. AVE RV ATTORNEY April 2, 1946.

9 Sheets-Sheet 5 .com

/NVENoR R. C. AVE RV April 2, 1946. R. c. AVERY TELEPHONE SYSTEM 9 Sheets-Sheet 6 Filed Sept. 26, 1944 v .NQQ v w1 m17@ Erni Y .Som .ogm mun.. ..-mlwl April 2, 1946..

R. c. AVERY TELPHONE SYSTEM Filed Sept. 26, 1944 9 Sheets-Sheet '7 /NVENTOR R. C. AVERY Bv l A ATTORNEY April 2, 41946.- R c, AVERY' 2,397,829

TELEPHONE SYSTEM Filed Sept. 26, 1944 f 9 Sheecs-She-ei'l 8 ALL THUN/f5 HUJY RELAY TRANSLATOR REGISTES RELAY:

IN TE RNE DA TE LTERNTE ROUTE l RELA Y 'l'l.- l

F/c. a

RELAY /NVENTOR R. C. AVERY Bwfm;

y A TTORNE Y April 2, 1946. R. c. AVERY 2,397,829

TELEPHONE SYSTEM I Filed sept. 26,v 1944 9 sheets-sheet 9 ATTORNEY Patented Apr. 2, -1946 TELEPHONE SYSTEM Robert Campbell Avery, Jackson Heights, N. Y., assignor to American Telephone and Telegraph Company,- a corporation of kNew York Application September 26, 1944, Serial No. 555,826

13 Claims.

This invention relates to telephone systems and has for its object to facilitate the provision of alternate routes between telephone exchanges.

Alternate routes have long been used in the establishment of toll connections under the manual control of the operator. 'I'he automatic selection of an alternate route through a tandem office in response to an all-trunks busy condition on the direct route has been suggested heretofore but in such 'prior arrangements only one alternate route of the type controlled by revertive pulsing has been provided and it has been necessary to include special equipment in the sender for each selection required for such an alternate route.

In accordance with the present invention it is possible to provide a plurality of alternate routes through a plurality of intermediate oices, all controlled by means of revertivepulsing. -In general, one set of selections determined by the marker may be used for the selections in any of the intermediate oflices, but should an additional set of selections be required in any one oilice, in accordance with a further feature of the invention these selections are controlled from one of the code registers of the sender. More specifically the A code register is used to control these Selections.

The invention will be more clearly understood from a consideration of the following description in connection with the drawings in which:

Figure 1 shows in diagrammatic form a direct route and two alternate routes between a calling and a called subscriber.

Figs. 2 to 5 show portions of a subscribers sender, Fig. 2 showing an oflice brushregister, an oiiice group register and certain other control relays, Fig. 3 showing the steering relays, Fig. 4 showing the counting relays and other control relays, and Fig. 5 showing a part of the'crossbar register as well as the marker connector.

Figs. 6 to 9 show portions of the marker, Fig. 6 showing parts of the oillce brush and oflice group registers, Fig. 7 showing parts of the class and compensating resistance registers, Fig. 8 showing the original route relay and one alternate route relay, and Fig. 9 showing two other alternate route relays; and

Fig. 10 shows the manner in'which Figs. 1 to 9 should be arranged.

In general the circuits disclosed in Figs. 2 to 5 are based upon the disclosure of United States Patent 2,106,360, toR. Raymond, VJanuary 25, 1938, and the circuits disclosed in Figs. 6 to 9 are based upon the disclosure of United States Patent 2,227,488, to Collis, Dehn, Hersey and Newsom, January 7, 1941. Wherever possible the same reference numerals are Yused as were used in the above patents. Y

In a system built up in accordance with the presentinvention, reversive pulsing is used in all alternate routes whichmay include one ofiice selector at an intermediate oiiice, a train of two oiiice selectors at such an olce, a cross-bar tandem cnice arranged for one set of office selections or a cross-bar tandemy office arranged for two sets of oiiice selections. In orderv that it shall not be necessary to establish a' different selection registration for each type of route,A the outgoing trunks to a given terminating oiiice are arranged to appear in corresponding positions in the outgoing frames of the intermediate offices.v Therefore, the same oiiice selections may be used for an alternate route requiring only one set of selections and for the Vsecond set of selections in routes requiring two sets of selections.

In intermediate offices requiring two sets of selections, the outgoing trunks and the secondary oice selectors are arranged in primary groups and the primary selectors have the function of selecting the required primary group. The primary group in which the outgoing trunks are located is determined by the iirst or A digit of the otlice code, and the group selections are under the control of that digit as .registered in the groups and the A code digit will be made more apparent hereinafter.

As shown in Fig. 1 if the subscriber at substation |09 wishes to talk with the subscriber at substation |0I associated with the called oice |02, the connection would normally be established through the district switches |20, |2| and oflice switches |30,` |3| to a trunk of trunk group |03 and through the equipment at the called Yoice |02 to the wanted line |0I. IiA all of the direct trunks leading to office |92 are busy,l the connection would then be set up over the district switches |20, |2|, oflice switches |00, IM, trunk |04 leading to the two-wire ofce selector |05 in the rst alternate oiiice |66 and thence over the trunk |01 to the called oiiice |02 and the wanted substation 0|. If all of the trunks leading to oillce |06 including trunk V|04 are also busy, a second alternate route will be employed leading from the district switches |20, |2| by way of oilice switches |50, |5| over trunk |00 to the two-wire office selector 109 and the three-wire ofce selector H at the common alternate oice I I and thence over trunk H5 to the called oiice |02 and the wanted substation IGI.

It is to be understood that the arrangement shown is merely illustrative. The direct and alternate route trunks may appear on the same oiiice frames, while in general the direct trunks to one oiiice would be spread over a number of switches in twoor more oiiice iframes.' Furthere more, while only two alternate routes have been shown, oneiemploying a single two-wire panel type ofce selector and the other a chain of two panel type selectors, more than two alternate` 'Y routes might be used, all of which might employ a single selector in the intermediate oices or all z path to an idle sender and operates select. and

hold magnets on the primary andsecondary line switches and sender link switches to Close that Path frQm the Subscribers line sito the sender. This connection is shown through linel switches lll and U2 and sender link switches land It! to the pulse receiving relays indicated by box l I3.

The subscriber then dials the oilice code ofthe desired terminating Ofce. Each digit is received by the pulse receiving relays I I3 and transmitted over Conductors indicated by cable H4 to the select magnets 530. of the cross-bar register switchv shown in Fig. 5 tol control the setting of the switch verticals. The first or A code digit is recorded on vertical V5,110, the second or B code digit is recorded on verticall and the third 01' C 00de digit iS recorded on vertical 520. When these three digits have been recorded relay 930 is operated', under the control of the hold magnet (not shown), which completes the operation oi the third digit vertical 52.9, as described the.. above-identiiied' Raymond patent. Relay 930, when operated. connects battery over the back. Contact of relay 933i to conductor 9M to cause the marker-connector' 54o tobe operated to connect, the sender with. idle. marker, for example the one partly shown' in Figs. 6 to 9. As shown in 55 and described in detail in the above-mentioned Raymond patent the cross-point of each digit register` grounds one or more of four conductors inaccordance with a code. The marker-connector S!) connects the twelve code conductors as well as the checking conductors through to theregisters of the marker indicated by the rectangle 150,

The registration set up on marker register 150 is transmitted to a set of translator relaysv 116i which bring about the operation of a certainroute relay such as relay 102. Three route relays 102, 153- and 800 may be usedin completing this call to its'destination. Relay 102 is denitely assigned to the particular oflice code which was dialed and no other. It operates when the o'iilce code has been received in the marker, ila/remainsoperatedl throughout this engagement of thev marker, it controls the testing of the trunks of the original route tothe terminating oflice and it transmits to the sender the information rer1u-ireo'A for the extension of the call to the terminating. cmce incase the original route is used and some other information required in case one of4 the alternate routes is used. Route relay 153 may be assigned to several oice codes for terminating offices reached by an alternate route through the two-wire cnice selector l05 at intermediate oiiice l06. This route relay is operated in case no idle trunk is found in the group of trunks leading directly to the wanted oice. It then remains operated throughout the engagement of the marker and controls the testing of the trunks of the alternate route. Route relay 800 is assigned .tot a large number of omce codes for terminating o iilces reached by a common alternate route through the common or tandem oiiice Il l. This route rela-y controls the testing of the group 0f trunks leading to the tandem office HI. Relay M0 is a route relay operated for the purpose of directing the call to an overow trunk in case no idle or alternate trunk can be found.

Corresponding armature springs of all route relays controlling original routes are multiplied to those of relay 102 as indicated, relays 1414, lii and '08 being common thereto. Similarly the armature springs of all route relays controlling intermediate alternate routes are multipled togetherV and are controlled by relays 101 and 10g, while the armature springs 0i all route relays controlling common alternate routes are multipled together andare controlled by relays 802 and 804. Armatures 1 to l0 of relay 10.2, armaof relays 8,00 and 8,10 are used for controlling the test of the group of voutgoing trunks by the marker.k These functions are described in the above-identified patent to Collis, Dehn, Hersey and Newsom, but since this operation is not an essential part of the present invention it will not be described, it being merely assumed that such test is performed. Y

Relay 102 in addition to controlling the test for an idle trunk outgoing to the wanted cnice, transmits information to. the sender. Conduotorl is normally connected to groundy at the back contact of the all-trunks-busy relay 6N- Therefore,

with relay 102 operated, ground is connected over contact. 3 of relay 106', contact d ofj relay 102 to conductor ,H6 and throughk the winding of relay 9H to battery. At, contactV 3 relayA 102 prepares a circuit lfrom conductor to conductor 'H2 through the upper windings of relays 952 and 912 to battery throughlthe winding of relay 9H. Y

Relays SIL/952, SIG, and 956 formv part of the olce group register of the marker. Contact 3 of route relay 102 and the corresponding contacts of other original route relays are cross-connected to the windings of the omce group relays in accordance with the omce group in which the trunks leading to the wanted oihce appear. Since, as pointed out above, all trunks leading to aparticular cnice are arranged to appear in the same position before the last ofce selector having accessl to that office, only a Single set of office selections is necessary. However, since in the typical trunk` arrangement employed for the present disclosure there is n o oice selector inthe original route, skip olice relayv 9H is operated to inform: fthe sender that no -oiilce selections are required on the original route, while the circuit prepared for relays 952, 912 and 941 prepares to identify the grouprof trunks recuiiredforv the alternate routes. Conductor H2 may be connected to either the upper or lower winding of the register relay, the upper winding being supplied by battery through the winding of relay all to add.

five` to the .numberoitno oiiioo group selected by Y the register relay. Conductor 1|2 may also be connected directly to the winding of relays 9|2, 9 |6, etc. to indicate that any secondary oillce selectors which may be used appear in the first primary group of the two '.suchgroups associated with the A digit of the oice code. When conductor i|2 is connected as shown through the windings of relays 952 and SI2, in series, or through any other similarpair of relays, a circuit is closed as pointed out hereinafter to modify any primary group selections to be made by the sender.

At its contact.2, route relay 102 closes acircuit from ground on conductor 63|, contact 3 of relay 104, contact 2 of relay 102, conductor 1|3`, lower winding of relay ||1 to battery. Relaysv |0|2 to |0|9 constitute the class register o the marker and serve to transmit to the sender an indication of the nature'of the terminating oilce and thereby the manner in which the called line designation is to be transmitted to-that oice. The contacts of the route relay may be cross-connected to either the upper or the lower windings of the register relays, the circuits through the upper windings being extended to the Winding of relay |0|9 -which serves to ground an additional conductor leading to the sender.

At its contact 5 route relay 102 closes a circuit from ground on conductor 63|, contact 4 of relay 106, contact 5 of relay 102, conductor 1 |5, through the lower winding of relay |009 to battery. Relays |000 to |0|0 constitute the compensating resistance register and serve to transmit to the sender an indication of the amount of resistance to be included in the fundamental circuit. As in the case of the other registers, the contacts of the route relays may becross-connected either to the lower windings which terminate directly in battery or to the upper` windings which extend to battery through the winding of relay |0|0. Relay |0|0 when operated causes the inclusion of a high resistance at a particular state of the operation of the sender.

At its contact relay 102 closes a circuit from ground on conductor 63|contact 2 of relay 104, contact of relay 102, conductor 1| |,'loWer winding of relay 901 to battery. Relays 900C to 9|0 constitute the oiii'ce brush register and serve to transmit to the sender an indication of the office brush selection to be made when such selection is required. As in the case of the other registers, the contact of the route relay may be cross-connected to either the upper or lower winding of the register relays, the upper winding being connected lto battery through the winding of relay 9|0 which is employed to transmit to the sender information concerning the number of digits to be expected.

It will be apparent that several other circuits are prepared by route relay 102 but these circuits do not become effective at this time.

The operation of route relay 102 has therefore served to operate registerA relays 901, 9|I, |009 and |0|1 thereby grounding conductors 520, 530, and 544. These conductors are connected l Relays 931and. |022 operate and prepare lock-` ing circuits for themselves to' conductorl 912. If the vmarker n'ds an idle direct trunk leading to theterminatingoiiice it grounds conductor 910 bringing about theoperation of relay 93| which in turn grounds conductor. 912 to lock-in the registrations set up under the control of the route relay 102. Themarker. then sets up a connection over'thedistrctand oiiice switches-to the selected trunk., 1

f `Direc route Let us assume rst that a direct connection has been successfully established. l As previously mentioned, when the code was recorded on the registers of Fig.,5, relay` 930 was operated, connectingbattery over the back contact of relay 93| tol conductor; 94|, to summon the marker. Whenthe marker grounds conductor 910 therefrom conductor 94|, causing the marker connector to release'and the marker to be made available for the decoding stage of another call. Relay 930. also connects'battery to conductor 915 thereby closing a circuit through the winding of relay |209 to ground at the upper back contact of relay |208, through thevwinding of relay |2|| to ground over a circuit not shown, and through the windingofrelay |235,*back contact of relay |232 to ground at the lower back contact of relay |208. Relays |209, |2|| and |235 are therefore normally operated after the marker has been seized. After the marker has'received and decoded the oiiice code resulting in the operation of the relay 931, it establishes a connection with the district and office switches and causes the sender to con-- neet ground to conductor 356. A circuit is thereupon closed to ground on conductor 350, front contact of relay 931, conductor 914, winding of relay .H06 tof battery on conductor 915. Relay ||06 operates, closing a locking circuit for itself through the winding of relay |||6, front contact of relay ||06 to ground at the upper back ccntact of relay .Relay |||6 cannot operate at this time being shunted by the operating circuit for relay H06. When the district and cnice by the marker connector 540 through to the'v sender where conductor 528 extends over conductor |024 to the upper winding of relay |022 and battery. Conductor 530 is extended over conductor 941 to the upper Winding of skip-cnice relay 931 and battery. Since the present invention is not concerned with the functions of the sender in connection with the completion of the call at a terminating ofllce,the class relays of the sender have been omitted. v

switches have been operated, ground is removed from conductor 356 and relay |||6 operates.

With relays H06 and |||6 operated, a trunk test circuit is vclosed extending from the ring f= conductor of the interoillce trunk through the omce and district switches, through the sender link switches to conductor 980, one or both of the resistances 9|0 and9||, selected in a manner similar to resistances 008R and 909R, conductor |2|, lower front contact of relay I I6, resistance 918,y conductor |255, winding of test relayv |20|, conductor 916, upper front'contact of relay H06, conductor |240, front contact of relay |209, back contact of relay |208 to conductor 351 and thence back to the tip conductor of the selected trunk. When theselectcr at the called cnice |02 is ready to make selections, battery and ground are connected to the circuit traced and relay |20| operates closing a circuit from battery on conductor 915, winding of relay |222, windings of relays |220 and |22| in parallel conductor |243, front contact of relay H06, conductor |256, to ground at the front contact of relay |20|. Relays |222, |22| and |220 operate and lock over the front contact ofrelay |222 to ground over the inner lower contact of relay 209. Relay |22| closes a circuit'frombattery on conductor 915, winding of relay ||0| backcontacts of relays |||2, ||,|3.,` |4-and |||5,^front'ccntact of relay |22] by operating relay93|, battery is disconnected and contact topground over conductor |244.` Relay cperatesinthis circuit closingaflocking circuit for itself, through the winding of relay ||||,front contact of relay ||0| to ground at theback con- -tact of relay |||2. Relay ||l| does notoperate at this time since its winding is shunted by the operating circuit for relayxlini. Relay ||0| also closes a circuitfrom ground Vat the upper back contact of relay |||3, upper front contact of relay |||6, upper front contact of relay. ||0|, Winding `of relay |208 to battery. Relay |208 opens the fundamental circuit permitting relay |20| to release.V It also opens the energizing circuit for relay |209 which now releases, opening theA locking circuits for relays |220 to |222 and permitting these relays to release. f When relay 22| releases relay I operates'opening thelocking circuit for relays ||00 Vand `|||i and theserelays release. The circuit vis now-ready to make incoming and :unalk selections .at theY called oice or to transmit the designation to that office in the way deter mined by the class registration derived from the route relay and the oce designation. Refer-` encefis made to the above-.identied Raymond patent for a description of the operations for controlling the terminating ofllce. v f

Intermediate alternate 'route of route relay 102, contact 5 ofA relay 106 to the.

winding of relay a and battery. Relay its operates in this circuit locking over itsy contact 3 ground from conductor 3| discon-v t0 ground under the controlof relay 6|0, and

Closings holding circuit for relay 6|0 over the upper contact of relay '5l rcontact of relay 108, contact of relay '|06 to oir-normal ground on conductor 628. Relay, 10B kat its contact V2 closes an obvious circuit for relay 106 which locks to Y off-normal ground on conductor 628. Relay 108 at its contact 2 also connects ground to conductor '|21 which eXtends overthe Contact 2 of relay |0| and, conductor 120.110. the winding of relay 104 and battery. Relay 104 operates in this circuit and is held operated over thev frontcontact of relay lotto grounded conductor 628. Relay l 106 opens the circuits for :controlling trunk selection, thereby releasing all connections between 1 the marker and the ole frame and inV turn releasing the all-trunks-busy relay 6| 0 and relay 103. When relay 108 reclosesits contact 4, it

. completes a circuit over'contact |0 of relay 106 |3 of the original route relay '|02 to' the winding of the intermediate alternate route relay153.

Y Reiay isiV at its contactarte 4 ,closes the on.

cuits for controlling thetest ofthe trunks leading to th'e'intermediate alternate oiice |06.` Since `the alternate route includes a two-wire olice selector, route relay 153 also closes a circuit from ground on kconductor 63|-, contact 9 of relay 101, contact 1 of relay 153, conductor 801,winding of relay |0|| to battery. Relay `|0|| at its contact Zopens the holding circuit;l for relay`194 and that relay releases to restore the circuitsv for setting up the ofce selection registration as well' as the laca. since relays mis` aecasae class registration. Atthi's ytime the' circuit for setting the compensating resistance register may beV traced from ground on conductor'GSl contacts I and 3 of relay |0| I, contact 6 of relay 95|, conductor'951, contact 5 of relay 104, Contact of relay 102, conductor 150 to the winding of relay |005 and battery. 'Relay |005 operates and connects ground to conductor 536 to prepare the operating circuitv for the compensating resistance register relay of the sender. With relay |0| I. operated, the circuit for setting the voilice group register may be traced from grounded conductor 03| over contact of relay |0||, conductor 125, contact 4 of relay 192, contact 3 of relay 102, conductor 'H2 to the upper Vwindings of relays 952 and 9|2, winding of relayi9| 1 andbattery. Relay 9|2 grounds conductor 532 and relay 9|1 grounds conductor 53| to operate thecorresponding ollce group register relays ofthe sender. Relay952 is inelective at this time. Relay' l0|| also grounds conductor 540 to operate the corresponding relay in the sender which is not shown. The circuit for oiice brush register relay 901 is closed as previously described, relay 901 grounding conductor 52B. The previously traced circuit for class register relay |0|1 is also closed. In the sender the'grounding of conductors 528, 532, 53|, and 536 causes the operation of compensating resistance relay SOIR, office brush register relay |022 and office group register relays |033 and |034. The skip oice relay 931 is normal. As described in connection with the directA route, when the marker has found an idle trunk to the intermediate alternate oil-ice |06, relay 93| is op- Y As previously described, when the marker hasfound an idle trunk, it causes the connection of ground to conductor 356. Sincerelay 931 is nt operated in this case, a :circuit is extended over the back contact of relay931, conductor 984, winding of relay |03 to battery on conductor 915. Relay H03 operates in this circuit and closes alocking circuit for itself through the Winding of relay 3, inner lower contact of. relay H03 to ground at the-,upper back. contact of relay |||4, but relay |||3 cannot operate, being shunted by the operating circuit of relay H03. When the marker has completed the connection with the selected trunk, ground is-removed from conductor 356 and relay |||3-operates. The fundamental circuit for testing the condition of the selected trunk is now completedthis circuit extending as previously tracedfrom-the ring conductor of the selected trunk to conductor 980,

front contact of relay |R, resistance 909B, backA contact of relay 902R, conductor I |32, front contact of relay |II3,conductor 985. resistance 918,

conductor |255, winding vof trunk test relay conductor 916l upper front contact of relay H03,

conductor |240, frontcontact of relay |209, back contact 9i relay 208, to conductor 351 and thence vback to the tip conductor of the selected trunk. Relay |29| operatesfin this test circuit as previously described, in turn operating relays |220 to |222 which lock `under thecontrol of relay and |||3 are operated,

the operation ,of relay I22|-closes a circuit from ground 0n conductor |294, contact of :relay |22|,

back contacts of relaysl I 5fand| Hd., frontcontact of relay |3, winding ofv relay ||04 to bat- I tery on conductor 915. Relay "I |04 operates andv locks through the winding yof'relay |'||4,"front 'contact of relay H04 to ground at the back contact of relay |||5. Relay |H4 does not operate being shunted by the operating circuit of relay H04. However, relay H04 closes a circuit from ground at the front contact of relay III3, front contact of relay I |04, winding of relay |208 and battery. Relay |208 opens the fundamental circuit, permitting relay `|20| to release. It opens the operating circuit for relay |209 which releases, 1.0

in turn releasing the counting relays |220 to |222. When relay I 22| releases, it opens the energizing circuit for relay II 04 permitting relay I4 to operate. Relay I4 in operating opens the locking circuit for relays H03 and 3 and these back contact of relay |208 to conductor 351.

Relay |202 in operating closes the counting relay circuit, which may be traced from lground at the front contact of relay |202, front contact of relay I2 I, back contact of relay |233, back contact of relay |223, conductor |248, front contact of relay I I I4, conductor |251, contact 3 of relay 550, conductor 55|, back contact of relay I 023, front contact of relay |022, back contact` of relay |02|,con

ductor 612, back contact of relay |225, winding i of relay |226, to battery on conductor 915.V Relay i226 operates in this circuit lockingithrough the winding of relay |22 5, front contact of relay |226, back contact of relay I 234 to ground at the upper contact of relay |209. Relay |225 does not operate at this time being shunted by the operating circuit of relay |226. At oilice |06 the selector |05 is moved upwardY in the brush selecting op'- eration and in such movement repeatedly connects a momentary ground to the fundamental circuit in shunt of the winding of stepping relay |202 and that relay releases at eachrevertive pulse. The first release permits relayv |225 to operate. When the momentary revertive ground is removed, relay |202 reoperates, reclo'sing the counting relay circuit which extends as previously traced to conductor 612 and Vover the front contact of relay |225 to the front contact of relay |235, the Winding of relay |224 and battery. Relay |224 operates and locks through the winding of relay |223, relay |223 remaining unopera'ted. A second revertive pulse permits relay |223ft'o operate. With relay |223 operated the counting relay circuit is extended-over the front contact of relay |223to conductor `610, backcontact of relay H05, conductor H26, Winding of relay |222 to battery.v Relay |222 operates, locking through the windings of relays |220 and |22| in parallel as previously described. The third revertive pulse permits the operation of relays I 220 and I 22|.

Since the fundamental circuit now extends over Aof the ninth pulse.

ferates-rela'y |201 which in turn operates relay |208 to bring about the release of relay |209, the release of the counting relays |220 to |226, the release of steering relays H04 and |II4, the operation of relay |||5 and the restoration of the fundamental circuit and the counting'relay circuit.

The fundamental circuit for office group selection is the same as traced for oflice brush selection except that it passes over the front contact of relay II I5 instead of the contact of relay I4. The counting relay circuit extends as previously traced to conductor |248 and thence over the inner upper front contact of relay |||5, conductor E258, contact 8 of relay 550, conductor 552,.front contact of relay |033, conductor 614, back contact of relay |229, Winding of relay |230 and battery. When relay |202 operates in the fundamental circuit, relay I-230 operates and locks through the Winding of relay |229, relay |229 operating in response tothe release of relay |202 by the first revertive pulse. When this pulse ends, relay |228 operates. In response to the next three revertive pulses, relays |221, |226, |225, |224 and |223l are operated and locked. As before, the

, operation of relay |223 transfers the counting relay circuit fromfconductor |248 to conductor 610, but with relay |05 operated this circuit now extends over the front contact of relay H05, frontV 'relay I 202 reoperates following the fifth revertive pulse, relay |232 operates, opens the operating circuit for relayV |235 and causes that relay to release.` 'The sixth, seventh, eighth and ninth pulses cause the operation of relays |23| to |225.

With relay |225 operated 'and relay |235 released,

the counting relay circuit is extended through the winding of relay |222 to battery so that relay |222 operates upon operation of relay |202 at the end The tenth revertive pulse causes the operation of relays |220 and I 22| in the locking circuit of relay |222.

The functions of relays |220 and |22| are substantially the same as previously described. Since relays ||05-and I5 are-operated during the olce group selection, the operation of relay |22| closes a circuit from ground over the front contact of f relay |22|, outer lower front contact of relay IH5, conductor 913, contact of relay 555i, conductors 553 and 914 to the Winding of relay H06 and battery. Relay H06 closes a circuit from ground at the front contact of Vrelay 'I l5, back contact of relay H03, front contact of relay H06, to the Winding of relay |201 and batter'y. Relay I 261 performs the function previously described for restoring the counting relays, releasing relays H05 'and ||I5 and operating relay |||6. With relays H06 and l||6 operated, v'the fundamental circuit for testing the trunk leading to the terminating ofce is completed and the functions of the sender continue asthough a directitrunl: had been selected at the beginning.

. Common alternate route Assume now that no trunks were available to -theintermediate alternate oiiice and it became j in the sender.

necessary to usethe common alternate group leading through oice II I. It will be remembered vthat when the marker tested the trunks to the I of relay 101 to off-normal ground on conductor 528. At contact 2 relay 109 closes an obvious circuit for relay 101-which locks over its contact 2 to o'normal ground on conductor 628, opening the holding circuit for relay 6I0 and the operating circuit for relay 109. At contacts 3, 4, 5 and relay '101 opens the circuits which control the selection of the trunk to the intermediate omce |05 and at contact 9 it opens the circuit'for Voperating relay IOI I. When the trunk test relays have released, relay 6I0 releases, in turn releasing relay 10S. When relay 109 releases it closes a circuit from ground, contact 4 of relay 10S;

contact 8 of relay 101, contact B of relay 153,'to the winding of common alternate route relay 800 and battery. i Y

Relay 800 at contacts 3- to 6 connects battery and ground to the circuits necessary for selecting an idle trunk to oce II5. At its contact I relay 000 closes a circuit from ground on conductor BSI, contact I of relay 802, contact I of relay 800, conductor 850, upper winding of primary oice relay 95| and battery. Relay 95| operates and extends its operating ground over its contact 2` to conductor 801 thereby operating relay IOII. With relay IEIII operated and -relay 104 non-operated, the same class and oflice selection register relaysV are operated. Relay95I is used to modify the selection of the compensating resistance in accordance with the'requirement of the common alternate route, whereby the circuit for operating the compensating resistance register extends from ground on conductor 63|, contacts I and 3 of relay IOI I, contact 5 of relay 95I, conductor 9,53, contact 6 of relay 104, contact I2 ofrelay 102, conductor 152, lower winding of relay I 000 and battery. With relay |000 operated ground is connected to conductors 536-and 531, causing ,change area, the secondary oiiiceselectors having access to the two largest numbers of oces will be arranged to appear in the primary office selector in groups of terminals individuallyv as` signed to the A digit and also in one of the groups of terminals-belonging to the two least congested digits, the latter group of terminals being placed directly above the former group of terminals. Similarly the selectors normally serving thelatter two digits are paired with those serving two other digits, with the terminals of the latter group above those of the former group,l etc. The two spare groups are paired with the fourth and eighth groups so assigned. Since the A code vertical may be cross-connected to the counting relays as desired, this arrangement .provides a considerable flexibility of distribution for the trunk groups and permits the location of excess trunk groups from congested digits in a second primary group while requiring only a simple adjustment ofthe selection at the primary office selector.

If a group of trunks is located in the primary oilice group identied bythe A digit of the corre- Y sponding orlice code, the office group register voperating circuits will be cross-connected to include only oney relay of the selected. pair of relays, for example, only relay SI2, while ifthe group of trunks is located in the second primary group, the

oflice group Y register operating circuit will be cross-connected to include both of the relays of the pair, that is both relays 952 and 9I2. Relay 052 has no function unless it becomes necessary to select a route leading through two oice selectors such as office I I I.

In this case the primary group relay v95| is operated and in combination with relay 952 closes ya circuit for group shift relay 050. Relay 95| grounds conductor 954 leading to the sender and relay 950 grounds conductor 955. Conductors 951i and 955 are extended over the marker-connector 540 to conductorsid and 555, respectively, op-

' erating relays 550 and` 556. Relay 550V locks in a .the operation of both relay 9|0R and relay 902B As mentioned hereinbefore, the individual offices of the exchange area have been grouped in accordance ,with the rst or A digit of the oice code. When so grouped, certain groups will be found to contain many more oices than others. reach all Yterminating oices through a common cnice, it is necessary to provide an additional orl Vprimaryplice selector, which may conveniently cess to ten groups of secondary office selectors j corresponding to theo ten digits. As is well known, the digits 1 and Y0v are not used as the first digit of an oflice code. Therefore there are two spare groups of terminals, In addition, while, as above mentioned, certain first digits correspond to large numbers of oihces, other rst digits represent only .a small number of oiiices. Assuming a typical ex-i In order to provide sufficient trunks tov circuit from batterythrough its lower winding and contact 6, conductor 551 .toV groundy at the lback contact of relay III5 and in a circuit from battery through its upper windingY and contact 5, conductor 560 to groundv at the back contact of relay III3. Relay 556 locks over its contact 1 to grounded conductor 912. l Y Y As in the case of the intermediate alternate cnice, Vsince relay 031 is not operated, the connection of ground to conductor 356 operates relay H03 and the disconnection of that ground permits the operation of relay II I3 in a locking circuit of relay H03. The fundamental circuit for testing the trunksto thecommon oiice is the k same as previously traced except that since both relays IR- and 902R are operated, neither of the resistances 908 and 909R are included in the circuit. The yoperation of relay I20I in thiscircuit causes the operation of relays |220 to I 222, as before, and relay I22I-operates relayl |04. The operation of relay. I208 vand the release of the count@ ing relays, followed by the operation of relay I I I 4,

.take place as previously described. yThe funda- |233, back contact of relay |223, conductor I248,

front Vcontact of relay- I H4, conductorl |251, con tact 4 of-relay 550, contact' 550 of the yA Vcode register vertical .500 (assuming that the A code digit was 4) conductor 61|, front contact of relay |235, Winding of'relay |2213 to battery on conductor dit. When the fundamental circuit is completed at the oiiice and relay |202 operates, this counting relay circuit is completed operating relay |224. As the primary oiiice selector |09 operates in its brush selecting function, it connects revertive pulses to the fundamental circuit, shunting relay` |202 as previously described. The first revertive pulse permits relay |223 to operate in the locking circuit of relay |224 While the second revertive pulse permits relays |220 and |22| to operate in the locking circuit of relay |222. Relay |22| operates relay ||05 and the operation of relays |201 and |208, release of relay |209, release of the counting relays, operation of relay |||5, the reestablishment of the fundamental circuit and the release of relays H04 and |||4 all take place as previously described.

With relays H05 'and |||5 operated, the counting relay circuit may be traced as above to conductor |248 and thence over the front contact of relay |||5, conductor |258, Vcontact 1 of relay 550, contact 559 of theA code register 500, contact 6 of relay 556 to'conductor 614, back contact of relay |229, winding of relay |230 to battery.v Five revertive pulses bring about the operation of relays |220 to |222, yrelay |220 opening the fundamental circuit to bring the selectorto rest, with the selected' brush set in position to hunt for an idle trunk inthe upper half of its terminal bank. VRelay in operating opens the locking circuit for relay 550 but that relay is now held operated in the circuit previously traced through its upper winding to ground at the back contact of relay |||3. Therefore when relay v|22| operates it closes a circuit from ground at its contact, over the front contact of relay |||5, conductor 013, contact 2 of relay 550. conductor 984, winding oi relay ||03 to battery. Relay H03 operates and locks through the Winding of relay I3 but relay l |3 is not operated at this time. Relay H03 operates relay |201 which in turn operates relay |208 releasingerelay |209 and the counting relays to permit the operation of relay I I3. Relays ||05 and |||5 are locked over conductor 56|, contact 0 of relay 550 to ground over conductor 12. Relay |||3 in operating opens the second l locking circuit for relay 550 and that relay releases, in turn releasing relays |05 and I l5. The sender is new ready to Vtest whether the secondary ofiice selector i0 is ready to operate. The trunk f test and selections are made precisely as for the oice selector at the intermediate alternate cnice, the setting of theoiiice brush and group registers being the samev as in that case, the only exception being that as previously'mentioned the fundamental circuit now contains a dinerent compensating resistance. A

Aspreviously mentioned, the cross-connections of the A code register tothecounting relays would be determined by Athe distribution of the cilice names among the code digits. For the typical arrangement disclosed,with relay 55E normal the digit 2 selects the Azero group, that'is the lower half or the bank served by the zero brush. With relay 555 operated the zero brush is also selected, cut it is positioned to hunt over the upper half of its bank or the No.1 primary oiiice group, which group is normally assigned to digit 8. With relay 556 operated, theregistration of digit 8 causes brush i to be selected and positioned to hunt over the lower half of its bank which is the No. 2 prition of the circuits controlled by relay 556 it willV be apparent that the A code digit as set upon the sender register determines the selection of a basic group of terminals at the primary cnice selector and that the operation of relay 555 under the contro1 of the marker causes the selection of the next higher group of terminals as a form of overflow group.

If all they trunks to the common alternate office are also busy, the operation of the al1-trunksbusy relay 6|0 may be used to operate the overow route relay |3|0.v i

It will be clear from a'considerationV of the foregoing description that any desirable number of alternate routes might be employed since the selection of the trunk to the alternate route oiice is under the control ofthe alternate route relay while the selections to be performed at the alter nate route oflice are determined by the original route .relay and the A code register if required. It is also apparent that crossbar tandem offices might also serve as alternate routes since they,

are also set by means fof revertive pulses.

What is claimed is: f

1. In a telephone system, an originating cnice, a terminating ofilce,-an1intermediate oflice, nrst trunks connecting said originating oice with said terminating oflice, otherl trunks connecting said originating .oiiice with said intermediate oiice-1 additional trunks connecting said intermediate cnice with said terminating cnice, a plurality of switches in said intermediate oiiice for connecting said other trunks to said additional trunks to constitute an alternate route between said originating onice and said terminating oiiice, a plurality of registers in said originating ofllce, a route relay, meansfor operating said route relay under the joint control of said plurality of registers, means under the control of said route relay for establishing a direct connection between said originat ing oilice and said terminating ofice over one of said irst trunks, and means effective if all of said iirst trunks are busy to operate said switches under the control of one of said registers and said route relay to establish an alternate connection through said intermediate otlce.

2. In a telephone system, an originating oflice, a terminating oiiice, an intermediate oiii-ce, first trunks connecting said originating ofce with said terminating ofiice, other trunks connecting said originating office with said intermediate ofce, additional trunks connecting said intermediate cnice with said terminating office, a train of selectors in said intermediate ofilce for connecting'said other trunks to saidr additional trunks to constitute an alternate routebetween said originating cnice and saidterminating oice, a plurality oi registers in saidoriginating oice, a route relay, means-for operatingfysaid route relay under the joint control of saidplurality of registers, means under vthe control of said route relay for establishing a direct connection between said originatins'k olice and saidterminating office over one of said rst trunks, and means effective if all oi said iirst trunks are busy to establish an alternate connection through said intermediate office, comprising means under the control ofV one of said Lregisters to' operate one of said selectors in said inmaryofce group. l'rixruary office group No. 2 is v termediate ooice 'and-means under the control of said route relayto operate the succeeding selector in said intermediate oillce; Y

3. In a, telephone system, an originating office, a terminating ofce, an intermediate cnice, rst trunks connecting said originating office with said terminating cnice, other trunks connecting said originating oflice with said intermediate office, additional trunks connecting said intermediate oiiiceV with said terminating office, a train of selectors in said intermediate cnice for connecting said other trunks to said additional trunks to constitute an alternate route between said originating office and said terminating oiiice, a plurality of registers in said originating oce, a route relay, means for operating saidroute relay under the joint controlof said plurality of .registersmeans under the control of said route relay'for establishing a direct connectionbetween said originating oflce and said terminating office over one of said first trunks, and means-effective if all of said rst trunks are busy to establish an alternate connection through said intermediate oiiice, comprising means under the'hcontrol of one of said registers'to operate one of said selectors in said intermediate-Omoo and means under the control of said route relay to operate` the succeeding selector in said intermediate cnice, and other means under the control of said route relay to modify the con trol of said one register.

4. In a telephone system, anoriginating oflice, a terminating olce, an intermediate oiiice, rst trunks connecting said originating oiiice with said terminating office, other trunks connecting said originating office with said intermediate oice, additional trunks connecting said intermediate oiice with said terminating office, primary and secondary o'ice selectors in said intermediate ofce for connecting said other trunks to said addi-` tional trunks Vto constitute an alternate route between'said originating oceand said terminat-` ing cnice, a plurality of registers in said originating oice, a route relay, means for operating said route relay under the joint control of said plurality of registers, means under the control of said route relay for establishing a direct connection between said originating oce and said terminating oiiice over one of said rst trunks, and means effective if all of said rst trunks are busy to establish an alternate connection through said intermediate oilice, comprising means under the control of one of said'registers to operate one of i said primary selectors insaid intermediate ofrice to select a group of secondary oiTlce selectors, i means under the control of said route relay to operate the selected secondary oiilce selector in said l intermediate oiiice, and other means under the control of said route relay to modify the control ci said one register to select a dierent group of secondary cnice selectors.

5. In a telephone system an originating of- Alce,-a terminating office, direct trunks connect- 1 ing said originating ofce and said terminating Voiiice, a first intermediate oilice, a rst group of alternate trunks connecting said originating ofce and said rst intermediate oice, oice seand appearing in a particular group of terminals ce, a. second group of alternate trunks connecting said originating oiiice with said second inter- 3 lectors at said rst intermediate o'rce,V a rst l group of terminating trunks connecting said first v intermediate oflice and said lterminating cnice,

mediate oice, primary and'secondary omce se- Y lectorsat said second intermediate office, aseo- Vroute relay,

ond group'of terminating-trunks .connecting said second intermediate" oiilce andv said terminating office and appearing before said secondary oice selectors in a group of .terminals corresponding to that occupied by said first group of terminating Vtrunks in said oice selectors, selection control equipment at said originating oilcameans in said selection control equipment to operate a route relay individual to said terminating office, and means under the control of said route relayvto set up a registration effective to control either said oiice selectors at said iirst intermediate oice or one of said secondary oiiice selectors rat said second intermediate oiiice toextend a connection to said terminating otlice.

6. In a telephone system an originating cnice, a terminating oiiicadrect trunks connecting said originating ofce and said terminating oce, a rst intermediate oice, a rst group of alternate trunks connecting said originating oflice landsaid intermediate oiiice, oiiice selectors at said rst ini group of terminals corresponding to that occupied by said first group of terminating trunks in said oiiice selectors, selection control equipment at said originating oilce comprising a' plurality of registers., a route relay individual to said terminating oice, means under the joint control of said plurality of registers for operating said means under theY control of said route relay to set up a-registration effective to control either said oiice selectors at said rst intermedi- Y ate oflice or one of said secondaryvoce selectors at said second intermediate oiiice to extend a connection to said terminating oce, and means undervthe control of oneof said registers to operate a primary oiice selector at saidsecond intermediate omce to select a secondary oice selector having access to said terminating office.

7.,In a telephone system an originating cnice, a terminating oflice, direct trunks connecting said originating office vand said terminating office, a rst intermediate o ilce, aA first group of alternate trunks connecting .said originating cnice and said intermediate oiiice, ollice selectors at said irstintermediate oiiice, a rst group of terminating trunks connecting said iirst intermediate oice Iand said terminating oice, and appearing in a particular group ofi terminals in said cnice selectors, a second intermediate office, a second group of alternate trunks connecting said originating oiice with said second Vintermediate oiilce, primary and secondary oflce selectors at said sec-- ond intermediate oce, a second group of terminating trunks connecting said second intermediate oiiice and said terminating oilice and ap-' aaoaeae f 9 relay, means under the control of said route rean intermediate office, other trunks connecting lay to set up a registration `effective to control said originating oiiice Vwith said vintermediate either said oilice selectors at said rst intermeoilice, completing trunks connecting said interdiate ofce or one of said secondary office selecmediate office with said terminating oilices, pritors at said second intermediate oiiice to extend a mary and secondary office selectors at said inter connection to said terminating oiice, means unmediate ofiice for connecting said other trunks der the control of one of said registers to operate with said completing trunks to constitute altera primary oiiice selector at said second intermenate routes between said originating oilice and diate office to select a secondary oiilce selector said terminating oices, said secondary oice seliaving access to said terminating oiiice, and lectors arranged in two adjacent groups before other means under the control of said route relay said primary yoffice selectors, registers in said tov modify the control of said one register over originating office for registering the three digits said primary oiice selectors. of the terminating office code, means under the 8. In a telephone system, an originating oiice, control ofthe first code register to control the a terminating croce, direct trunks connecting operation of said primary oiioe Selector to select said originating oice and said terminating oiilce, one of said groups of secondary oiice selectors, a first intermediate oiilce, a iirst group oi alterand means under the control of all of said regisnate trunks connecting said originating office and ters for modifying the control exerted by said said intermediate oiiice, oiilce selectors at said rst code register to cause the selection of the iirst intermediate ofilce, a first group of terminatadjacent group of secondary oiiice selectors. ing trunks connecting said irst intermediate 11. In a telephone system an originating oillce, oiice and said terminating oiiice, and appearing a terminating oflce, direct trunks connecting said in a particular group of terminals in said oflice originating oiice and said terminating oilce,` a selectors, a second intermediate ofiice, a second rst intermediate oflice, a rst group of alternate group of alternate trunks connecting said origitrunks connecting said originating office andsaid nating oice with said second intermediate cnice, intermediate oflice, oice selectors at said nrst primary and secondary office selectors at said secintermediate oilce, a rst group of terminating ond intermediate office, a second group of -ter- Ytrunks connecting said rst intermediate oilice minating trunks connecting said second interand said terminating oflice, a second intermediate mediate oice and said terminating office and ofce, a second group of alternate trunksv conappearing beforesaid secondary office selectors neet/ing Said Originating ofllce with said second inin agroup of terminals corresponding to that termediate oiiice, primary7 and secondary office occupied by said first group of terminating trunks selectors at said second intermediate ovflice, asecin said ofce selectors, selection control equipond'group of terminating trunksconnecting said ment at said originating oilice comprising a plusecond intermediate office and said terminating rality of registers, a route relay individual to said oiiice, selection Control equipment at Said Origiterminating office, means under the joint control Hating Oiliee, including o plurality 0f Code regisof said plurality of registers for operating said ters, means under the joint control of all of said route relay, means under the control of said route Code registers for Operating a route relay indirelay to set up a registration effective to control 40 Vidul t0 Said terminating Oil-loe, means under eithersaid orllce selectors at said rst intermethe control of said route relay for Selecting an diate oiice or one oi said secondary office selecidle Path to said terminating oiiiee, said selecting tors at said second intermediate oflice to extend means effective to successively test Said direttr a connection to said terminating oiiice, and trunks, said trunks to said first intermediate ofmeans under the joint control of one of said regiee and said trunks to said second intermediate isters and said route relay to operate one of said office, a series of steering relays, means under the primary office selectors at said second interme- Control of said steering relays for operating Said diate oii'ice to select a secondary office selector selectors, and means under the control of said having access to said terminating oiiice. route relay for preventing the operation of said 9. In a telephone system, an originating olce, 5o steering relays, for operating Said Steering relays e, plurality of terminating offices identified by through a single cycle of operations or for operthree digit codes, direct trunks connecting said ating said steering relays through a plurality of originating office with said terminating oirices, cycles in accordance with the selected path to an intermediate office, other trunks connecting said terminating oiiice. said originating oiice with said intermediate 12. In a telephone system an originating Omoo oiice, completing trunks connecting said intera terminating office, direct trunks connecting said mediate office with said terminating oiices, prioriginating office and said terminating ofce, a mary and secondary oiice selectors at said interrSt intermediate oiliee, a rSt group of alternate mediate office for connecting said other trunks trunks Connecting said originating omce and said with said completing trunks to constitute alter- 6o intermediate office, o'ce selectors at said first innate routes between said originating oiice and termediate office, a rSt group of terminating said terminating offices, said secondary ofiice setrunks connecting said first intermediate ofce lectors arranged in basic groups and overiiow and said terminating oiiice, and appearing in a groups in accordance with the iirst digit of said particular group of terminals in said oilice secode, means to control the operation of saidA lectors, a Second intermediate oiice, a second primary oiiice selectors in accordance with said group of alternate trunks Connecting Said origirst digit to select a basic group of office selechating Ooe With Said Second intermediate Omoo, tors and means at said originating oflice operated primary and Secondary oiiiee Selectors at said in accordance with the complete code to modify second intermediate oiiice, a second group of terthe control of said primary oirlce selectors to seminating trunks connecting said second intermelect an overiiow group of selectors. diate office and said terminating oilice and ap- 10. In a telephone system, an originating office, pearing before said secondary ofce selectors in a plurality of terminating oilices identified by a group of terminals corresponding to thatoc` three digit codes, direct trunks connecting said cupied by said first group of terminating trunks originating oflice with said terminating omces, in said oice selectors, selection control equipment-at saidlordginating onine; inciildingfaplmraf'litywof: code registers;y 'means under :the-kcontrol ofsaid'oode; registersv for operating..zagronterelay individual, .to said. terminatingzofee, :means thez uontrol' .of said route. .relays :for fseleotng an idle-path to. said terminating o'lce,.said lsalenting means .effective to .successively-test saiddreet trunks;` saidtrunksoto said rstintermediate oi;- ne and: saidltrunks4 to said second. intermediate oflice-meansunder the1control..,of saidzrcmte"relai7 fori-.setting 11p a. registrationidentifying; the.I sition oisaid terminating trnnksmeans. .under the control of; one of said. codee'registerszonidenf the positionv of sai-d` secondarywofloe; seslectursr beforeV said primary: oilioe selectors; a serieseoi-steeringfrelays, ,rneansz1inelen the. control o ,fsaic steering relays# :for operating selec;- tors, andL means under `the oontnoloffsaidlroute relay-fior.-` preventing the-operation;oirsaidteerf ing relaysl, 'for operating =sant v-steeringprrelays througghgasinglezicyclefofoperationein conneotion -withaid route relay'oontrolled'identifitingmeams or. orgoperatingzsaid steering relayathnough-,tmo eyclesoi operation; in connection witlrgsaid code register controlled: identifying1V means andi said route.; relayicontrolled identifyingzmeans; faef oordancewthzthe selected paths-to said: terminat; ingoflice, e

. Y Inea-telephone.systemengoriginatingoffioe,

a; terminating: onine.; direct trunks: :connectingsaid-v originatingoice andesaid terniinatingfoloe; a;irstmtermediataoioei ia... :tirs/t; gnou-nofaiter'- nate trnnlas` .connecting said originating fofliee and said intermediate oilee.; oce; selectors; :at Y

said;1rst ;intermediate.oieaeatrstisgnonp of-rtervrxnnatnte trunks;A reonneeting; said; iirst.. intermenienteA oiee :and said terminating; oicaandgap pearingain azpartieularfgroup:.ofrtenminaflsinsaid omee selettore, `a;sescondinterrnediatefoine; alsnog:-

ond; :group kof alternate trunks: -eonneetinss said originating office. Withsaidzk seconde :intermediate oitme;A primary# andjseoondary otlice; selectoraat saidseeund intermediate; omce,,-asecondagnoupof terminating', :trunks connecting .said ,second termediate oice,- and, smid; 'terminating` unice-and appearing heforesaid secondary ofce; selectors in. jafgroup.- of; :terminals corresponding to that oeoupiedtby'saidiristgroup of terminatingvftrnnks in' said.-v oce; selectors,- seleetion control equip;- 'ment at: saiol` originating oce including- :at plu? -raflity oi code; regsters, means under thefcontro'l of said code registersrfor-operating aroute, relay individual to;` saida tenminating, yoiiicej .means under; the control3 oisaid route; relayf forzselectf idle, path; toi said: terminating; yortica, x'miti selecting means1-leieetive;*to-' sueeessivelytest-said direct;v trunks; said; trunks4 o; saidrst internmeniateaofee :ancllsaiditrunkswto sadeseeondtintenmediate; :oloe,,. means; 'under `the eontrol..'of :said routarelay'- for setting; .up a: registration identifyii-ngf the, posi-tion :of saidf terminating, trunks, vmeans-- under controll of one .of-,saidfcode -registers for; identifying; the position. of 4saidV seeondaryfoi.- noe; selectorsv before: -said pri-mary,I office selectors, a primary officie,l selection relay. operatedl if; the pathseleetecl;Y extends through said second intermediatezoice, assetof steering relays-:for control,- ling seleetions at'said intermediate oices,-,;means to: operate said `steering i-relayst .through oneaexcle in; |r:. nr1ection-` withsaid coolerV reg-istei` controlled identifying mea-na meansiresponsine tothe com .pletiorr` oi` sai`d-one 4,cyele to release. Ysaicllonlin:arr-ft' oiceselection relayfantl meansfto thereafterfopt. erate; said .steeringV relays. through t-av-seeong ,oy-ole connection with said, noutef relay, controlled identifyingzmeans.; Y

ROBERT CAMPBELLAVEMG 

